-LRB- CNN -RRB- -- Federal terrorism charges against Boston Marathon bombings suspect Dzhokar Tsarnaev could be filed soon , even as he remains hospitalized , a Justice Department official told CNN on Saturday . The 19-year-old could also face murder charges at the state level .

At the Beth Israel Deaconess Medical Center , where Tsarnaev was in serious condition while being held in federal custody , federal prosecutors were formulating the charges .

The development came amid questions as to what 's next for the suspect in the Boston Marathon bombings .

President Barack Obama said he 's keenly interested in answers .

`` There are still many unanswered questions , '' Obama said Friday night . `` Why did these young men who grew up and studied here as part of our communities and our country resort to such violence ? How did they plan and carry out these attacks ? And did they receive any help ? The families of those killed so senselessly deserve answers . ''

Tsarnaev and his older brother , Tamerlan Tsarnaev , are accused of setting off bombs at the marathon Monday , killing three people and wounding more than 170 .

On Thursday night , they allegedly killed a Massachusetts Institute of Technology police officer before the older brother was killed during a shootout with police .

Dzhokar Tsarnaev was captured Friday night after he was found hiding in a boat in a backyard in Watertown , Massachusetts .

When will the suspect be in court ?

Tsarnaev could be in a courtroom for an arraignment soon .

Ordinarily at an arraignment , the suspect is provided a lawyer , and the defense and prosecution try to make a case for whether he should be released on bail .

`` He will not get bail obviously , '' said senior legal analyst Jeffrey Toobin .

`` They will set a preliminary hearing that could happen in the next 30 days . He will be indicted with the grand jury . And that 's when the case will begin . ''

After the charges are filed , the Federal Public Defender Office in Boston will be appointed to represent Tsarnaev , according to Miriam Conrad , the federal public defender for the Massachusetts district .

Should bomber suspect be questioned without a lawyer ?

For now , the government is invoking the public safety exception , a designation that allows investigators to question Tsarnaev without reading him his Miranda rights , a Justice Department official told CNN on condition of anonymity .

In ordinary cases , a suspect is told by police he has the right to remain silent and he has the right to a lawyer .

But this is not an ordinary case , say U.S. Sens. John McCain and Lindsey Graham .

They urged that Tsarnaev be held as an `` enemy combatant , '' a designation that allows a suspect to be questioned without a lawyer and without being informed of his Miranda rights .

`` Now that the suspect is in custody , the last thing we should want is for him to remain silent . It is absolutely vital the suspect be questioned for intelligence gathering purposes , '' the senators said . `` Under the law of war we can hold this suspect as a potential enemy combatant not entitled to Miranda warnings or the appointment of counsel . ''

But Sen. Carl Levin , D-Michigan , chairman of the Senate Armed Services Committee , said Saturday that the suspect should not be held as an enemy combatant .

`` I am not aware of any evidence so far that the Boston suspect is part of any organized group , let alone al Qaeda , the Taliban , or one of their affiliates -- the only organizations whose members are subject to detention under the Authorization for Use of Military Force , as it has been consistently interpreted by all three branches of our government , '' he said .

`` In the absence of such evidence I know of no legal basis for his detention as an enemy combatant . To hold the suspect as an enemy combatant under these circumstances would be contrary to our laws and may even jeopardize our efforts to prosecute him for his crimes . ''

Alan Dershowitz , a prominent defense attorney and Harvard law professor , scoffed at the Republican senators ' statement .

`` Impossible . There 's no way an American citizen committing a domestic crime in the city of Boston could be tried as an enemy combatant , '' he told CNN 's Piers Morgan . `` It could never happen . And that shows absolute ignorance of the law . ''

Dershowitz also said statements made by police in Boston seems to contradict the government 's reasons for invoking the public safety exception .

`` The police have said there 's no public safety issue ; it 's solved , it 's over , '' Dershowitz said . `` There are no further threats . But the FBI is saying there 's enough further threats to justify an exception . ''

Former New York Mayor Rudy Giuliani said the federal government may have known about international threats about which state officials were not aware .

`` You would have to know the internals of what they have before you can assess whether there is a sensible invocation or not , '' Giuliani said .

If the government had prior knowledge of Tsarnaev 's activities , it has n't disclosed it . It did say that Tamerlan Tsarnaev had been on the FBI 's radar in the past .

FBI agents interviewed Tamerlan two years ago and also looked at his travel history , checked databases for derogatory information and searched for Web postings . The agency found no connection with terror groups , an FBI official told CNN .

Two key Republicans on the House Homeland Security Committee -- Rep. Mike McCaul of Texas , the panel 's chairman ; and Rep. Peter King of New York -- will press the Obama administration for details about the FBI 's questioning of Tamerlan Tsarnaev , according to a GOP congressional source .

Tamerlan Tsarnaev , who was not a U.S. citizen , traveled to Sheremetyevo , Russia , in January 2012 , according to travel records provided by a U.S. official . He returned six months later .

Federal or state trial ?

Dershowitz said there are many arguments that can be made to try the case in state court . It may be hard for a prosecutor to prove which crimes were committed by Tsarnaev or his older brother , Dershowitz said .

`` If he says my intent was to please my brother , they could raise the question of federal jurisdiction , '' Dershowitz said .

This fight over federal or state jurisdiction could mean life or death .

Massachusetts does not have the death penalty .

There 's another big question : The National Defense Authorization Act of 2012 requires temporary military custody of certain terrorist suspects , but Dzhokar Tsarnaev is a U.S. citizen , and the act does n't apply to Americans .

What is the reaction in the suspects ' homeland ?

Tsarnaev 's family lives in the Russian republic of Dagestan , which is next to the suspects ' homeland of Chechnya , located in the North Caucasus region of southern Russia .

Russia 's investigative committee in Dagestan said it will not engage with the Tsarnaev family unless there is `` an order from above '' to do so , spokesman Rasul Temerbekov told Russian state news agency RIA Novosti on Saturday .

A spokesman for Russian President Vladimir Putin said Saturday that Russia wants to get official information from the United States about the bombing suspects , and he wants there to be contact between investigators in both countries .

CNN 's Lorenzo Ferrigno and Dana Bash contributed to this report .

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NEW : Federal Public Defender Office in Boston to represent Dzhokar Tsarnaev after charges are filed

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Russian President Vladimir Putin wants details from U.S. on bombing suspects

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If physically able , suspect could be in court this weekend , expert says

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Two U.S. senators say Dzhokar Tsarnaev should be questioned without a lawyer